Attempts at manufacturing superconducting thin films by forming a superconducting layer including an oxide superconductor as a main component on a metallic substrate have been frequently suggested. Among these, a superconducting wire, which is obtained by forming an oxide superconductor expressed by a compositional formula of REBa2Cu3O7-d (the oxide superconductor is called an RE-based superconductor, d represents a non-stoichiometric amount of oxygen, and RE represents a rare-earth element) on a tape-shaped metallic substrate, may obtain high current characteristics. Therefore, currently, the superconducting wire is one of superconducting films for which research and development is being actively conducted. In addition, a stage has been reached at which a number of trial products related to electric power equipment or the like using the superconducting wire are being manufactured.
Accordingly, in technology for manufacturing a superconducting thin film starting with the superconducting wire, it is preferable to establish a mass production system for industrialization as a manufacturing process, and development of a stable process with high reliability has become a matter of considerable urgency.
However, in a stage of manufacturing the superconducting thin film, metal elements making up the metallic substrate diffuse, and thus, at an interface between the metallic substrate and an upper layer (an intermediate layer or a superconducting layer) above the metallic substrate, the metal elements partially undergo an oxidation reaction, or the metal elements partially undergo an interfacial reaction with a constituent material of the upper layer. As a result, peeling-off of a formed layer may occur.
Therefore, Patent Document 1 (Japanese Patent Application Laid-Open (JP-A) No. 2010-123475) discloses a method for manufacturing a superconducting thin film. In the method, a metal oxide layer including chromium oxide as a main component is formed immediately over a metallic substrate including an Ni-based alloy, and then a superconducting layer is formed on the metal oxide layer in order to suppress diffusion of metal elements of the metallic substrate and to suppress a reaction of the metal elements, which leads to peeling-off.